Introduction: force on an object, then the acceleration


Roads are much more dangerous than we think,
Car safety features nowadays are the only things giving us the chance of
surviving a crash. The first practical and modern automobile was invented in
1985 by Karl Benz as a means of easy transportation in the near future. Karl’s
invention and imagination now became a reality, cars are used by everyone everywhere
and is the number one choice of transportation in 2017. Even though Karl’s idea
was spectacular, many flaws occurred as we as a race developed and more cars were
being produced. Problems such as deadly, life threatening accidents began to
occur which is what caused us to create car safety features to prevent the passing
of more people due to cars. These new and improved “Car safety features” were
created/introduced using Isaac Newton’s three laws of physics.


Newton’s three laws of motion:

             Newton’s first law also known as
Inertia is the disability of an object to change its status of motion on its
own (more mass à more Inertia), thus meaning that when there is no net
force the object is at rest and will stay at rest, and if the object is moving
with a constant velocity if will stay moving with a constant velocity.

second law states that when there is a net force on an object, then the
acceleration of that object is directly proportional () to the net force. So, “as the force acting upon an object is increased, the acceleration of the
object is increased. As the mass of an object is increased, the acceleration of
the object is decreased.” (physicsclassroom) consequently, à concluding that  and . His second law in terms of the amount of motion also known as momentum
() shows that (. The change in momentum is known as Impulse, it can be concluded that  and calculated using the equation

Finally, Isaac Newton’s third
law explains that when object 1 exerts a force on object
2, object 2 will exert an equal and opposite force on 1, summarised as for every action
force there is a reaction force equal and opposite to the action force (FAB = -FBA) as shown in illustration 1.0.

three laws are simple but are implicated and play a big role in car safety features.


Moving objects such as cars have kinetic
energy while in motion which we all know cannot be produced or destroyed, as
the vehicle brakes, that energy transforms into heat energy which are transferred
to the surroundings of that vehicle by the brakes. Cars nowadays have many
features that absorb that energy, minimizing the impact of the collision during
an accident to insure human safety. These modern safety features normally
include airbags, seatbelts and even crumple zones.







Car safety features:



Airbags relate to Newton’s first law of how when an object is in motion,
it stays in motion until it is acted upon with an unbalanced force .

Airbags are one of the safety features implemented all around a vehicle but
most importantly in the steering wheel and the front passenger dashboard. During
a collision, the driver tends to hit the steering wheel, the front passenger
hits the dashboard while the passengers in the back hit the seats. The airbags
are placed/designed to cushion the impact and prevent the passengers from
hitting their heads and causing damage to the brain or skull, as soon as
the airbags react to the force produced from the collision, it will
inflate itself, preventing the passengers and driver from hitting anything in
front of them. The airbags act as the unbalanced force used
to distribute the persons inertia decreasing the impact on the human body. Although
airbags are very useful, they don’t prevent injuries from happening, for
example if the collision was from the side of the car, airbags wouldn’t be
great help as they are mostly in the front making them pointless. They do not
prevent you from getting thrown out of the windshield or being hit by the car.

These are some reasons we also encourage the use of the second safety feature;



             It is illegal all-around the world
nowadays to not wear your seat belt while in a vehicle, seatbelts are extremely
common and important found almost in every movable vehicle especially cars and
planes. The 48mm in width typical seatbelt is manufactured using a soft
material such as polyester webbing, polyester webbing is used to prevent the
seatbelt from causing any cuts or major injuries when coming in contact with
the human body under high speeds and forces. Seatbelts are attached to the cars
frame, this is to insure the humans stable place as one with the seat, during
collision, the seatbelt will prevent the human from hiqtting their head and
exiting through the windshield. Seatbelts are retractable as they can be easily
shifted, however, during an emergency brake, the seatbelts lock holding the
person tight which relate to Newton’s law of Inertia (). Seatbelts are in cars to the effects of Inertia. If the car was moving
80km/h and comes into contact with another car, the person would strike into
the windshield because of Newton’s first law where an object that is in motion
will remain in motion until an unbalanced force is exerted on it, when the car
collides, your body will continue traveling at a constant speed until you
strike the dashboard or windshield (more mass à more Inertia). Thus, the
seatbelt is that unbalanced force that holds the person down protecting them
from their own Inertia.


second law of forces depicts that of seatbelts, the proper use of a seat
belt reduces the external force of an accident and disperses the initial
inertia of the collision across the body. Without a seat belt, the
passenger’s acceleration combined with the car’s deceleration, increases the
total acceleration. When this acceleration is being multiplied by a very large
mass, even a small change in acceleration results in a large increase in the
force being applied to the body of the human.


 The third major safety feature in
cars nowadays are crumple zones, crumple zones work according to the two laws
(law of Inertia and Newton’s second law). They are placed on both front and
back of the car and are made to deform during collision, they absorb the impact
energy developed during the crash allowing less energy to be placed on the
passengers. While the front and back of the cars are made to deform in order to
increase the time taken for the automobile to come to a stop (longer time taken
to stop = less Inertia and momentum), the frame of the car where the passengers
are seated is made out of high strength steal and many support beams.



Before these applications were discovered, a
vast majority of accidents lead to death due the lack of safety features in the
car or automobile. For instance, without seatbelts, the passengers would continue
moving even after the car stops suddenly leading to many injuries. Without
airbags car crashed lead to breakage to the skull and even rupture to the brain
leading to death. Before crumple zones, most of the force of the accident would
be directed/passed onto the passengers leading to more injuries and even death.

Benefits and limitations of safety automobile features:

             As most things, car safety features
have its benefits and limitations. Advantages being that many lives are saved
everyday due airbags, seatbelts and crumple zones. In 2006 alone, 15,000 people
were saved because of seatbelt usage, seatbelts prevent drivers from getting
discharged out of their seats during an incident, now statistics show that more
than 75% of drivers not wearing seatbelts were killed. Airbags have proven to
save many life’s and in fact even with
the protection of seatbelts and crumple zones in the event of a crash, the
chance of surviving a serious crash with airbags increase significantly.

Although there are
advantages of car safety features, there are also disadvantages, some being
that; airbags are designed to protect but in some cases the deployment of the
airbags can severely injure the passengers who may be improperly positioned.

Airbags can be most harmful to children and infants as the force of the deployment may be too strong for
them causing very severe injuries and even death. Seatbelts in many cases can
cause serious damage to internal organs like tearing of the colon or diaphragm.

In some cases, the lumbar vertebrae may even be fractured or dislocated. One
major disadvantage of the crumple zones is that the automobile may very well be
no longer